RESUMEN
Dihydroxyacetone phosphate (DHAP)-dependent aldolases catalyze the aldol addition of DHAP to a variety of aldehydes and generate compounds with two stereocenters. This reaction is useful to synthesize chiral acyclic nucleosides, which constitute a well-known class of antiviral drugs currently used. In such compounds, the chirality of the aliphatic chain, which mimics the open pentose residue, is crucial for activity. In this work, three DHAP-dependent aldolases: fructose-1,6-biphosphate aldolase from rabbit muscle, rhanmulose-1-phosphate aldolase from Thermotoga maritima, and fuculose-1-phosphate aldolase from Escherichia coli, were used as biocatalysts. Aldehyde derivatives of thymine and cytosine were used as acceptor substrates, generating new acyclic nucleoside analogues containing two new stereocenters with conversion yields between 70% and 90%. Moreover, structural analyses by molecular docking were carried out to gain insights into the diasteromeric excess observed.
Asunto(s)
Aldehído-Liasas , Escherichia coli , Fructosa-Bifosfato Aldolasa , Simulación del Acoplamiento Molecular , Nucleósidos de Pirimidina , Thermotoga maritima , Animales , Escherichia coli/enzimología , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/síntesis química , Aldehído-Liasas/metabolismo , Aldehído-Liasas/química , Conejos , Fructosa-Bifosfato Aldolasa/química , Fructosa-Bifosfato Aldolasa/metabolismo , Thermotoga maritima/enzimología , Dihidroxiacetona Fosfato/metabolismo , Dihidroxiacetona Fosfato/química , EstereoisomerismoRESUMEN
The manuscript reports on 7-deazapurine and pyrimidine nucleoside and oligonucleotide cycloadducts formed by the inverse electron demand Diels-Alder (iEDDA) reaction with 3,6-di(pyrid-2-yl)-1,2,4,5-tetrazine. Cycloadducts were constructed from ethynylated and vinylated nucleobases. Oligonucleotides were synthesized containing iEDDA modifications, and the impact on duplex stability was investigated. iEDDA reactions were performed on nucleoside triple bond side chains. Oxidation was not required in these cases as dihydropyridazine intermediates are not formed. In contrast, oxidation is necessary for reactions performed on alkenyl compounds. This was verified on 5-vinyl-2'-deoxyuridine. A diastereomeric mixture of 1,2-dihydropyridazine cycloadduct intermediates was isolated, characterized, and later oxidized. 12-mer oligonucleotides containing 1,2-pyridazine inverse Diels-Alder cycloadducts and their precursors were hybridized to short DNA duplexes. For that, a series of phosphoramidites was prepared. DNA duplexes with 7-functionalized 7-deazaadenines and 5-functionalized pyrimidines display high duplex stability when spacer units are present between nucleobases and pyridazine cycloadducts. A direct connectivity of the pyridazine moiety to nucleobases as reported for metabolic labeling of vinyl nucleosides reduced duplex stability strongly. Oligonucleotides bearing linkers with and without pyridazine cycloadducts attached to the 7-deazaadenine nucleobase significantly reduced mismatch formation with dC and dG.
Asunto(s)
Emparejamiento Base , Reacción de Cicloadición , Oligonucleótidos , Piridazinas , Piridazinas/química , Oligonucleótidos/química , Purinas/química , Estructura Molecular , Nucleósidos de Pirimidina/química , ADN/química , Disparidad de Par BaseRESUMEN
A simple, reliable, and efficient method for the gram-scale chemical synthesis of pyrimidine nucleosides functionalized with C5-carboxyl, nitrile, ester, amide, or amidine, starting from unprotected uridine and cytidine, is described. The protocol involves the synthesis of 5-trifluoromethyluridine and 5-trifluoromethylcytidine with Langlois reagent (CF3 SO2 Na) in the presence of tert-butyl hydroperoxide and subsequent transformation of the CF3 group to the C5-C 'carbon substituents' under alkaline conditions. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Synthesis and characterization of 5-trifluoromethyluridine (5-CF3 U) and 5-trifluoromethylcytidine (5-CF3 C) Basic Protocol 2: Conversion of 5-CF3 U and 5-CF3 C to several C5-substituted ribonucleosides.
Asunto(s)
Química Orgánica , Nucleósidos de Pirimidina , Citidina/análogos & derivados , Nucleósidos de Pirimidina/síntesis química , Nucleósidos de Pirimidina/química , Ribonucleósidos/química , Uridina/análogos & derivados , Química Orgánica/métodosRESUMEN
To understand the regioselectivity observed in the allylation of pyrimidine nucleosides and to identify the factors directing the reaction, a theoretical study of the regioselective allylation was carried out. Several key points were considered such as: the structure of the deprotonated nucleobase in the presence of Na+; the effect of the solvent on the dissociation and aggregation reactions of thymidine/Na+ ion pair; and the likely allylation reaction mechanisms involved. The results showed that the regioselectivity observed experimentally can be attributed to a greater stability of a dimeric form coupled to an increase of the reaction barrier in THF due to larger Na+ binding to the nucleobase.
Asunto(s)
Nucleósidos de Pirimidina , Nucleósidos de Pirimidina/química , TimidinaRESUMEN
Enzymes from thermophilic organisms are interesting biocatalysts for a wide variety of applications in organic synthesis, biotechnology, and molecular biology. Next to an increased stability at elevated temperatures, they were described to show a wider substrate spectrum than their mesophilic counterparts. To identify thermostable biocatalysts for the synthesis of nucleotide analogs, we performed a database search on the carbohydrate and nucleotide metabolism of Thermotoga maritima. After expression and purification of 13 enzyme candidates involved in nucleotide synthesis, these enzymes were screened for their substrate scope. We found that the synthesis of 2'-deoxynucleoside 5'-monophosphates (dNMPs) and uridine 5'-monophosphate from nucleosides was catalyzed by the already known wide-spectrum thymidine kinase and the ribokinase. In contrast, no NMP-forming activity was detected for adenosine-specific kinase, uridine kinase, or nucleotidase. The NMP kinases (NMPKs) and the pyruvate-phosphate-dikinase of T. maritima exhibited a rather specific substrate spectrum for the phosphorylation of NMPs, while pyruvate kinase, acetate kinase, and three of the NMPKs showed a broad substrate scope with (2'-deoxy)nucleoside 5'-diphosphates as substrates. Based on these promising results, TmNMPKs were applied in enzymatic cascade reactions for nucleoside 5'-triphosphate synthesis using four modified pyrimidine nucleosides and four purine NMPs as substrates, and we determined that base- and sugar-modified substrates were accepted. In summary, besides the already reported TmTK, NMPKs of T. maritima were identified to be interesting enzyme candidates for the enzymatic production of modified nucleotides.
Asunto(s)
Nucleósido-Fosfato Quinasa , Thermotoga maritima , Nucleótidos/química , Fosforilación , Nucleósidos de Pirimidina/química , Especificidad por Sustrato , Thermotoga maritima/enzimología , Thermotoga maritima/genética , Uridina Monofosfato/metabolismo , Nucleósido-Fosfato Quinasa/genética , Nucleósido-Fosfato Quinasa/metabolismoRESUMEN
A chemical reinvestigation of the Indonesian strain Streptomyces sp. SHP 22-7 led to the isolation of three new pyrimidine nucleosides, along with six known analogues and zincphyrin. The structures of the new compounds (6, 7, 10) were elucidated by employing spectroscopic techniques (NMR, MS, CD, and IR) as well as enantioselective analyses of methyl branched side chain configurations. Application of the precursor-directed feeding approach led to the production and partial isolation of nine further pyrimidine analogues. The new compounds 6, 7, and 11 and three of the known compounds (2-4) were found to possess antimycobacterial and cytotoxic properties.
Asunto(s)
Nucleósidos de Pirimidina , Streptomyces , Vías Biosintéticas , Disacáridos , Estructura Molecular , Nucleósidos , Nucleósidos de Pirimidina/química , Streptomyces/químicaRESUMEN
DNA owes its remarkable photostability to its building blocks-the nucleosides-that efficiently dissipate the energy acquired upon ultraviolet light absorption. The mechanism occurring on a sub-picosecond time scale has been a matter of intense debate. Here we combine sub-30-fs transient absorption spectroscopy experiments with broad spectral coverage and state-of-the-art mixed quantum-classical dynamics with spectral signal simulations to resolve the early steps of the deactivation mechanisms of uridine (Urd) and 5-methyluridine (5mUrd) in aqueous solution. We track the wave packet motion from the Franck-Condon region to the conical intersections (CIs) with the ground state and observe spectral signatures of excited-state vibrational modes. 5mUrd exhibits an order of magnitude longer lifetime with respect to Urd due to the solvent reorganization needed to facilitate bulky methyl group motions leading to the CI. This activates potentially lesion-inducing dynamics such as ring opening. Involvement of the 1nπ* state is found to be negligible.
Asunto(s)
Nucleósidos de Pirimidina/química , Procesos Fotoquímicos , Nucleósidos de Pirimidina/efectos de la radiación , Pirimidinas/química , Pirimidinas/efectos de la radiación , Solventes/química , Espectrofotometría Ultravioleta , Rayos Ultravioleta , Uridina/análogos & derivados , Uridina/química , Uridina/efectos de la radiación , VibraciónRESUMEN
We herein report new 5-substituted uridine derivatives as potent inhibitors of mycobacteria - causative agents of tuberculosis. A series of new 5-alkynyl-substituted uridine derivatives were synthesised via palladium-catalysed Sonogashira cross-coupling reaction of 5-iodo-6-methylpyrimidine base with terminal acetylenes with good yields in DMF at room temperature. It was found that methyl group in C-6 position of pyrimidine ring had no impact on yields of target compounds. All obtained compounds were evaluated for their antimycobacterial activity against Mycobacetrium bovis and Mycobacterium tuberculosis at concentrations of 1-100 µg/ml using MABA test. Synthesized nucleosides showed high antimycobacterial activity against M. bovis and M. Tuberculosis. The MIC50 values of 11 and 13 were similar or close to that of the reference drug rifampicin.
Asunto(s)
Antituberculosos/farmacología , Diseño de Fármacos , Mycobacterium bovis/efectos de los fármacos , Mycobacterium tuberculosis/efectos de los fármacos , Nucleósidos de Pirimidina/farmacología , Antituberculosos/síntesis química , Antituberculosos/química , Relación Dosis-Respuesta a Droga , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Nucleósidos de Pirimidina/síntesis química , Nucleósidos de Pirimidina/química , Relación Estructura-ActividadRESUMEN
Bioactivity-guided chromatographic methods are of great significance for the isolation of the active compounds in complex samples. In this study, four anti-fungal compounds were located by activity screening and successfully isolated from a microbial fermentation sample by preparative high-performance liquid chromatography. Separation performance of columns including C18, positively charged C18, negatively charged C18 and C8 were firstly investigated. And it showed a better capacity of mixed-mode stationary phases for retention and separation. Therefore, the positively charged C18 column was used to separate the sample into several fractions, among which the active one was identified by the antifungal test. And then the active fraction was enriched and separated again by successively using the negatively charged C18 and C8 columns to obtain four compounds, which were identified as polyoxins A, K, F and H. With activity verification, four polyoxins were found to have good inhibitory effects against the three fungal plant diseases including rice sheath blight, tomato grey mould disease, and apple spot leaf disease.
Asunto(s)
Antifúngicos/aislamiento & purificación , Antifúngicos/química , Antifúngicos/metabolismo , Cromatografía Líquida de Alta Presión , Fermentación , Estructura Molecular , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/aislamiento & purificación , Nucleósidos de Pirimidina/metabolismoRESUMEN
Natural products with a high ratio of sp3-hybridized atoms and oxygen-substituted stereogenic centers represent privileged structures for the development of pharmaceuticals and chemical probes. The multiple oxygen functionalities of these natural products endow their potent and selective biological activities, although they significantly heighten the challenge of their chemical assemblies. We focused on developing efficient strategies for the total syntheses of this biologically and chemically important class of molecules. A convergent strategy is more advantageous than a linear strategy for designing a shorter synthetic route because a convergent strategy enables direct coupling of functionalized fragments whereas a linear strategy involves stepwise construction of a molecule from its terminus. Radical reactions are preferred over polar reactions for the coupling of heavily functionalized and sp3-rich fragments, as they allow for C(sp3)-C(sp3) coupling without damaging diverse polar functional groups. With these considerations in mind, we designed radical-based convergent strategies for assembling highly oxygenated natural products. Here we summarize the concise total syntheses of asimicin (1, antibiotic activity), 1-hydroxytaxinine (2, cytotoxicity), polyoxins (3, antifungal activity), and hikizimycin (4, anthelmintic activity) as representative examples. Retrosynthetic disconnection at the central part of these molecules produces highly substituted α-alkoxy radicals as synthons. In the synthetic direction, the α-alkoxy radicals were generated from the corresponding α-alkoxyacyl tellurides in a unified fashion, and then utilized for four distinct coupling reactions. Formation of the Et radical from Et3B and O2 homolytically cleaves the C-Te bond of α-alkoxyacyl telluride, and the facile expulsion of carbon monoxide from the acyl radical leads to the α-alkoxy radical. Dimerization of the stabilized α-alkoxy radical resulted in the core structure of 1 with 10 contiguous stereocenters. The coupling adduct was derivatized to 1 through the attachment of two different carbon chains (17 steps as the longest linear sequence). Alternatively, intermolecular addition reactions of the α-alkoxy radicals to electron-deficient CâC, CâN, and CâO bonds, followed by Et3B-mediated radical termination, led to the core structures of 2, 3, and 4, respectively. Intermolecular coupling between the α-alkoxy radical and the cyclohexenone derivative and intramolecular pinacol coupling gave rise to the 6/8/6-fused ring system of 2, which was transformed to 2 (26 steps). The two amino acid moieties of 3 were prepared by combining the α-alkoxy radical and the oxime and were then condensed to complete the synthesis of 3 (11 steps). Furthermore, a combination of α-alkoxyacyl telluride and Et3B/O2 realized a novel addition reaction of α-alkoxy radicals to aldehydes. This method was incorporated in the construction of the core 4-amino-5-deoxyundecose with 10 contiguous stereocenters, which was fabricated with two appendage structures to deliver 4. The four total syntheses described here demonstrate the versatility and robustness of intermolecular radical reactions. These syntheses will also provide new insights for retrosynthetic analyses in the field of organic chemistry and streamline synthetic routes to various bioactive natural products with multiple oxygen functionalities.
Asunto(s)
Productos Biológicos/síntesis química , Radicales Libres/química , Oxígeno/química , Aminoglicósidos/química , Productos Biológicos/química , Diseño de Fármacos , Furanos/síntesis química , Furanos/química , Nucleósidos de Pirimidina/síntesis química , Nucleósidos de Pirimidina/química , Teoría Cuántica , Estereoisomerismo , Taxoides/síntesis química , Taxoides/químicaRESUMEN
Nucleosidic and oligonucleotidic diarylethenes (DAEs) are an emerging class of photochromes with high application potential. However, their further development is hampered by the poor understanding of how the chemical structure modulates the photochromic properties. Here we synthesized 26 systematically varied deoxyuridine- and deoxycytidine-derived DAEs and analyzed reaction quantum yields, composition of the photostationary states, thermal and photochemical stability, and reversibility. This analysis identified two high-performance photoswitches with near-quantitative, fully reversible back-and-forth switching and no detectable thermal or photochemical deterioration. When incorporated into an oligonucleotide with the sequence of a promotor, the nucleotides maintained their photochromism and allowed the modulation of the transcription activity of T7 RNA polymerase with an up to 2.4-fold turn-off factor, demonstrating the potential for optochemical control of biological processes.
Asunto(s)
ARN Polimerasas Dirigidas por ADN/antagonistas & inhibidores , Desarrollo de Medicamentos , Inhibidores Enzimáticos/farmacología , Etilenos/farmacología , Oligonucleótidos/farmacología , Nucleósidos de Pirimidina/farmacología , Proteínas Virales/antagonistas & inhibidores , Bacteriófago T7/enzimología , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Etilenos/síntesis química , Etilenos/química , Oligonucleótidos/síntesis química , Oligonucleótidos/química , Procesos Fotoquímicos , Nucleósidos de Pirimidina/síntesis química , Nucleósidos de Pirimidina/química , Proteínas Virales/genética , Proteínas Virales/metabolismoRESUMEN
A novel methodology to access alkynyl nucleoside analogues is elaborated. Highly fluorescent 5-alkynylfuropyrimidines were synthesized (97-46%) and their antiviral properties investigated in vitro. Regiochemistry of the functionalization was achieved with the aid of 5-endo-dig electrophilic halocyclization of acetyl 5-p-tolyl- or 5-p-pentylphenyl-2'-deoxyuridine. Structure of one of the resulting nucleosides, 6-p-tolyl-5-iodo-2'-deoxyribofuranosyl-furo[2,3-d]pyrimidin-2-one, was confirmed by X-ray crystallography, and its conformation was compared to related nucleosides. Diverse alkynyl substituents were introduced at the heterobicyclic base C-5 position via Sonogashira coupling of 5-iodo-2'-deoxyribofuranosyl-furo[2,3-d]pyrimidin-2-ones. The resulting compounds had fluorescence emissions of 452-481 nm. High quantum yields of 0.53-0.60 were observed for 9-ethynyl-9-fluorenol and propargyl alcohol/methyl ether-modified furopyrimidines. These modified nucleosides, designed in the form of ribose acetyl esters, are potential tools for fluorescent tagging, studying nucleoside metabolism, 2'-deoxyribonucleoside kinase activity, and antiviral activity. Antiviral assays against a broad spectrum of DNA and RNA viruses showed that in human embryonic lung (HEL) cell cultures some of the compounds posess antiviral activity (EC50 1.3-13.2 µM) against varicella-zoster virus (VZV). The alkynyl furopyrimidine with two p-pentylphenyl substituents emerged as the best compound with reasonable and selective anti-VZV activity, confirming p-pentylphenyl potency as a pharmacophore.
Asunto(s)
Antivirales/química , Antivirales/farmacología , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/farmacología , Antivirales/síntesis química , Línea Celular , Fluorescencia , Halogenación , Herpesvirus Humano 3/efectos de los fármacos , Humanos , Modelos Moleculares , Nucleósidos de Pirimidina/síntesis química , Infección por el Virus de la Varicela-Zóster/tratamiento farmacológico , Infección por el Virus de la Varicela-Zóster/virologíaRESUMEN
The notion of using synthetic heterocycles instead of the native bases to interface with DNA and RNA has been explored for nearly 60 years. Unnatural bases compatible with the DNA/RNA coding interface have the potential to expand the genetic code and co-opt the machinery of biology to access new macromolecular function; accordingly, this body of research is core to synthetic biology. While much of the literature on artificial bases focuses on code expansion, there is a significant and growing effort on docking synthetic heterocycles to noncoding nucleic acid interfaces; this approach seeks to illuminate major processes of nucleic acids, including regulation of transcription, translation, transport, and transcript lifetimes. These major avenues of research at the coding and noncoding interfaces have in common fundamental principles in molecular recognition. Herein, we provide an overview of foundational literature in biophysics of base recognition and unnatural bases in coding to provide context for the developing area of targeting noncoding nucleic acid interfaces with synthetic bases, with a focus on systems developed through iterative design and biophysical study.
Asunto(s)
ADN/metabolismo , ARN/metabolismo , Emparejamiento Base , ADN/química , Enlace de Hidrógeno , Nucleósidos de Purina/química , Nucleósidos de Purina/metabolismo , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/metabolismo , ARN/química , Biología Sintética/métodosRESUMEN
Methods for rapid and high-throughput screening of transcription in vitro to examine reaction conditions, enzyme mutants, promoter variants, and small molecule modulators can be extremely valuable tools. However, these techniques may be difficult to establish or inaccessible to many researchers. To develop a straightforward and cost-effective platform for assessing transcription in vitro, we used the "Broccoli" RNA aptamer as a direct, real-time fluorescent transcript readout. To demonstrate the utility of our approach, we screened the effect of common reaction conditions and components on bacteriophage T7 RNA polymerase (RNAP) activity using a common quantitative PCR instrument for fluorescence detection. Several essential conditions for in vitro transcription by T7 RNAP were confirmed with this assay, including the importance of enzyme and substrate concentrations, covariation of magnesium and nucleoside triphosphates, and the effects of several typical additives. When we used this method to assess all possible point mutants of a canonical T7 RNAP promoter, our results coincided well with previous reports. This approach should translate well to a broad variety of bacteriophage in vitro transcription systems and provides a platform for developing fluorescence-based readouts of more complex transcription systems in vitro.
Asunto(s)
Aptámeros de Nucleótidos/genética , Bioensayo , ARN Polimerasas Dirigidas por ADN/genética , ADN/genética , Reacción en Cadena de la Polimerasa/métodos , Proteínas Virales/genética , Secuencia de Aminoácidos , Aptámeros de Nucleótidos/química , Aptámeros de Nucleótidos/metabolismo , Secuencia de Bases , ADN/química , ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/química , ARN Polimerasas Dirigidas por ADN/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Regulación de la Expresión Génica , Magnesio/química , Magnesio/farmacología , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Mutación Puntual , Regiones Promotoras Genéticas , Nucleósidos de Purina/química , Nucleósidos de Purina/farmacología , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/farmacología , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Cloruro de Sodio/química , Cloruro de Sodio/farmacología , Espectrometría de Fluorescencia , Espermidina/química , Espermidina/farmacología , Fracciones Subcelulares/metabolismo , Transcripción Genética , Proteínas Virales/química , Proteínas Virales/metabolismoRESUMEN
5-Hydroxymethylcytosine and uracil are epigenetic nucleobases, but their biological roles are still unclear. We present the synthesis of 2-nitrobenzyl photocaged 5-hydroxymethyl-2'-deoxycytidine and uridine 3'-O-phosphoramidites and their use in automated solid-phase synthesis of oligonucleotides (ONs) modified at specific positions. The ONs were used as primers for PCR to construct DNA templates modified in the promoter region that allowed switching of transcription through photochemical uncaging.
Asunto(s)
5-Metilcitosina/análogos & derivados , ADN/química , Desoxicitidina/química , Oligonucleótidos/síntesis química , Compuestos Organofosforados/química , Uracilo/química , Uridina/análogos & derivados , 5-Metilcitosina/síntesis química , 5-Metilcitosina/química , Epigénesis Genética , Epigenómica , Estructura Molecular , Oligonucleótidos/química , Nucleósidos de Pirimidina/química , Uridina/químicaRESUMEN
Inhibition of DNA repair enzymes tyrosyl-DNA phosphodiesterase 1 and poly(ADP-ribose)polymerases 1 and 2 in the presence of pyrimidine nucleoside derivatives was studied here. New effective Tdp1 inhibitors were found in a series of nucleoside derivatives possessing 2',3',5'-tri-O-benzoyl-d-ribofuranose and 5-substituted uracil moieties and have half-maximal inhibitory concentrations (IC50) in the lower micromolar and submicromolar range. 2',3',5'-Tri-O-benzoyl-5-iodouridine manifested the strongest inhibitory effect on Tdp1 (IC50 = 0.6 µM). A decrease in the number of benzoic acid residues led to a marked decline in the inhibitory activity, and pyrimidine nucleosides lacking lipophilic groups (uridine, 5-fluorouridine, 5-chlorouridine, 5-bromouridine, 5-iodouridine, and ribothymidine) did not cause noticeable inhibition of Tdp1 (IC50 > 50 µM). No PARP1/2 inhibitors were found among the studied compounds (residual activity in the presence of 1 mM substances was 50-100%). Several O-benzoylated uridine and cytidine derivatives strengthened the action of topotecan on HeLa cervical cancer cells.
Asunto(s)
Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Interacciones Hidrofóbicas e Hidrofílicas , Hidrolasas Diéster Fosfóricas/metabolismo , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/farmacología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/toxicidad , Células HeLa , Humanos , Nucleósidos de Pirimidina/toxicidadRESUMEN
The nature of the first genetic polymer is the subject of major debate1. Although the 'RNA world' theory suggests that RNA was the first replicable information carrier of the prebiotic era-that is, prior to the dawn of life2,3-other evidence implies that life may have started with a heterogeneous nucleic acid genetic system that included both RNA and DNA4. Such a theory streamlines the eventual 'genetic takeover' of homogeneous DNA from RNA as the principal information-storage molecule, but requires a selective abiotic synthesis of both RNA and DNA building blocks in the same local primordial geochemical scenario. Here we demonstrate a high-yielding, completely stereo-, regio- and furanosyl-selective prebiotic synthesis of the purine deoxyribonucleosides: deoxyadenosine and deoxyinosine. Our synthesis uses key intermediates in the prebiotic synthesis of the canonical pyrimidine ribonucleosides (cytidine and uridine), and we show that, once generated, the pyrimidines persist throughout the synthesis of the purine deoxyribonucleosides, leading to a mixture of deoxyadenosine, deoxyinosine, cytidine and uridine. These results support the notion that purine deoxyribonucleosides and pyrimidine ribonucleosides may have coexisted before the emergence of life5.
Asunto(s)
ADN/química , Evolución Química , Origen de la Vida , Nucleósidos de Purina/síntesis química , Nucleósidos de Pirimidina/síntesis química , ARN/química , Adenosina/análogos & derivados , Adenosina/química , Citidina/química , ADN/genética , Oxidación-Reducción/efectos de la radiación , Nucleósidos de Purina/química , Nucleósidos de Purina/genética , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/genética , ARN/genética , Uridina/químicaRESUMEN
The chromatographic behavior of a kind of nucleoside peptides, polyoxins, was investigated in this study. Molecular simulation technique was used to elucidate the temperature-dependent peak sharpening of polyoxins. There was a relatively small energy barrier between the global minimum conformer and the local minimum conformer of polyoxin A and the high temperature helped to quickly cross the energy barrier and accelerate the conformational transformation for getting the global minimum, so that stationary phase could not identify these two conformations and presented a sharp peak. Two kinds of mixed-mode columns, strong cation exchange or strong anion exchange ligands bonded with C18 (C18SCX and C18SAX) were used to improve separation selectivity of four polyoxins (A, K, F, H). The electrostatic attraction was necessary to increase the retention to ensure that the alkyl chain can give better play to its hydrophobic effect. Therefore, four polyoxins were well separated on C18SCX at pH 2 and they were also well separated on C18SAX at pH 7. In the small-scale purification of polyoxins, the sample loading of the C18SCX was five times than that of the C18SAX and the purity of the collected four polyoxins was all over 90%.
Asunto(s)
Cromatografía Líquida de Alta Presión , Concentración de Iones de Hidrógeno , Conformación Molecular , Simulación de Dinámica Molecular , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/aislamiento & purificación , Sales (Química)/químicaRESUMEN
In search of new anti-tuberculars compatible with anti-retroviral therapy we re-identified amicetin as a lead compound. Amicetin's binding to the 70S ribosomal subunit of Thermus thermophilus (Tth) has been unambiguously determined by crystallography and reveals it to occupy the peptidyl transferase center P-site of the ribosome. The amicetin binding site overlaps significantly with that of the well-known protein synthesis inhibitor balsticidinâ S. Amicetin, however, is the first compound structurally characterized to bind to the P-site with demonstrated selectivity for the inhibition of prokaryotic translation. The natural product-ribosome structure enabled the synthesis of simplified analogues that retained both potency and selectivity for the inhibition of prokaryotic translation.
Asunto(s)
Antituberculosos/química , Diseño de Fármacos , Péptidos/química , Piranos/química , Animales , Antituberculosos/farmacología , Chlorocebus aethiops , Cristalografía por Rayos X , Humanos , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis/efectos de los fármacos , Nucleósidos de Pirimidina/química , Células THP-1 , Thermus thermophilus/química , Células VeroRESUMEN
Synthesis of 2'-O,5'-C-bridged-ß-d-homolyxofuranosyl nucleosides U and T have been achieved starting from diacetone-d-glucose in overall yields 55.7 and 57.1%, respectively. Quantitative regioselective monoacetylation of the lone primary hydroxyl group in trihydroxy nucleoside intermediate, i.e. 3'-O-benzyl-ß-d-glucofuranosyl nucleosides mediated by Novozyme®-435 has been utilized as the key step in the synthesis of homolyxofuranosyl nucleosides. The structure of the synthesized 2'-O,5'-C-bridged-ß-d-homolyxofuranosyl uracil and -thymine has been established on the basis of their spectral (IR, 1H, 13C NMR and HRMS) data analysis and the structure of earlier nucleoside was confirmed by its X-rays diffraction analysis which revealed that these 2'-O,5'-C-bridged homo-nucleosides are locked into S-type sugar puckering.